Biosorption of copper ions through microalgae from piggery digestate: Optimization, kinetic, isotherm and mechanism

The remediation of heavy metal contaminated wastewater using microalgae has attracted more and more attention. In this study, the removal of copper (II) from piggery digestate by Desmodesmus sp. CHX1 was investigated. Results showed that the optimal conditions for copper (II) removal by Desmodesmus sp. CHX1 were pH of 6.00, microalgae inoculation concentration of 0.41 g/L and treatment time of 4 d, with the copper removal efficiency of 88.35%. The biosorption process of copper (II) by Desmodesmus sp. CHX1 under optimal conditions well followed the pseudo second order model, with the rate constant and the theoretical and experimental biosorption capacity of 0.15 mg/(L.h) and 0.85 mg/L, respectively. The isotherms adsorption of copper was described well by the Langmuir model, biosorption maybe dominated the adsorption process. The affinity of Cu2+ by functional groups in the microalgal cell walls was the main mechanism for copper removal by Desmodesmus sp. CHX1.